Indoor plants in homes and commercial buildings such as malls, offices, airports, and hotels, can benefit from precision irrigation to maintain healthy growth and reduce water consumption. As active valves are too costly, and ongoing precise manual adjustment of drip emitters is impractical, we explore how the Toyota HSR mobile manipulator robot can autonomously adjust low-cost passive emitters. To provide sufficient accuracy for gripper alignment, we designed a lightweight, modular Emitter Localization Device (ELD) with cameras and LEDs that can be non-invasively mounted on the arm. This paper presents details of the design, algorithms, and experiments with adjusting emitters using a two-phase procedure: (1) aligning the robot base using the build-in hand camera, and (2) aligning the gripper axis with the emitter axis using the ELD. We report success rates and sensitivity analysis to tune computer vision parameters and joint motor gains. Experiments suggest that emitters can be adjusted with 95 % success rate in approximately 20 seconds.